Probability question

In a population, 10% have 1 story home, 50% have 2 story home and 40% have 3 story home, after speaking with 300 people, what is the chance that more than 40% live in a 3 story homes?
the answer is 0.5 but how to get to this? thanks!

What an odd question.

1) You have established that 40% live in 3-stories. The probability that more than 40% live in 3-stories is 0. Why do we care how many you ask?

2) If you mean what propotion of the SAMPLE live in 30-stories, that is a different question. 40% is the expected value of the proportion. The probability of greater than that is 50% and the probability of less than that is 50%...or am I confusing mean and median? You tell me.